Superabsorbent polymer and method for preparing the same

Abstract

The present invention relates to superabsorbent polymer having an improved absorption speed through micropores formed inside, and a method for preparing the same.

What is claimed is: 
     
       1. A superabsorbent polymer, comprising:
 a base resin powder comprising a crosslinked homopolymer of acrylic acid monomers having acid groups of which at least a part are neutralized, 
 wherein a plurality of pores with a diameter of 1 μm or more are formed in the base resin powder, 
 wherein the crosslinked homopolymer comprises layered silicate-based particles dispersed in a crosslinking structure, 
 wherein the layered silicate-based particles comprise hectorite, 
 wherein the superabsorbent polymer has a time for removing vortex generated of 60 seconds or less when stirring 2 grams of the superabsorbent polymer at 600 rpm in 50 ml of a 0.9 wt % NaCl solution, and 
 wherein a centrifuge retention capacity for a saline solution, measured according to EDANA method WSP 241.2, is 45 g/g or more. 
 
     
     
       2. The superabsorbent polymer according to  claim 1 , wherein the plurality of pores with a diameter of 1 μm or more formed in the base resin powder comprise micropores with diameters of 10 μm to 100 μm. 
     
     
       3. The superabsorbent polymer according to  claim 1 , wherein the layered silicate-based particles comprise a unit crystal comprising a metal oxide layer, and a silica layer comprising silica formed on at least one side of the metal oxide layer. 
     
     
       4. The superabsorbent polymer according to  claim 1 , wherein the layered silicate-based particles have a column structure with a maximum diameter of a cross section of 1 nm to 100 nm, and a height of 0.1 nm to 20 nm. 
     
     
       5. The superabsorbent polymer according to  claim 1 , wherein the layered silicate-based particles are included in the content of 0.01 parts by weight to 5 parts by weight, based on 100 parts by weight of the base resin powder. 
     
     
       6. The superabsorbent polymer according to  claim 1 , wherein the crosslinked homopolymer comprises a crosslinking structure in which polymer chains of the acrylic acid monomers are crosslinked through crosslinkable functional groups of an internal crosslinking agent. 
     
     
       7. The superabsorbent polymer according to  claim 1 , wherein the crosslinked homopolymer comprises a crosslinked homopolymer formed by polymerization of the acrylic acid monomers in the presence of an internal crosslinking agent comprising a multifunctional acrylate-based compound. 
     
     
       8. The superabsorbent polymer according to  claim 6 , wherein the internal crosslinking agent comprises one or more selected from the group consisting of polyethyleneglycol diacrylate(PEGDA), glycerin diacrylate glycerin triacrylate, non-modified or ethoxylated trimethylol propane triacrylate(TMPTA), hexanedioldiacrylate, and triethyleneglycol diacrylate. 
     
     
       9. A method for preparing a superabsorbent polymer comprising steps of:
 conducting a crosslinking polymerization of acrylic acid monomers having acid groups of which at least a part are neutralized, in the presence of layered silicate-based particles comprised hectorite, a blowing agent and an internal crosslinking agent, to form a hydrogel polymer; and
 drying, grinding and sieving the hydrogel polymer to form a base resin powder, wherein the superabsorbent polymer comprises: 
 
 the base resin powder comprising a crosslinked homopolymer of the acrylic acid monomers having acid groups of which at least a part are neutralized, 
 wherein a plurality of pores with a diameter of 1 μm or more are formed in the base resin powder, 
 wherein the crosslinked homopolymer comprises the layered silicate-based particles dispersed in a crosslinking structure, 
 wherein the superabsorbent polymer has a time for removing vortex generated of 60 seconds or less when stirring 2 grams of the superabsorbent polymer at 600 rpm in 50 ml of a 0.9 wt % NaCl solution, and 
 wherein a centrifuge retention capacity for a saline solution, measured according to EDANA method WSP 241.2, is 45 g/g or more. 
 
     
     
       10. The method for preparing superabsorbent polymer according to  claim 9 , wherein, in the step of forming the hydrogel polymer, based on 100 parts by weight of the blowing agent, 1 to 1000 parts by weight of the layered silicate-based particles are used. 
     
     
       11. The method for preparing superabsorbent polymer according to  claim 9 , wherein the step of forming hydrogel polymer comprises steps of
 forming a first solution comprising the internal crosslinking agent, and the acrylic acid monomers having acid groups of which at least a part are neutralized; 
 forming a second solution comprising the layered silicate-based particles and the blowing agent; and 
 progressing the crosslinking polymerization of a monomer composition comprising the first solution and the second solution. 
 
     
     
       12. The method for preparing superabsorbent polymer according to  claim 11 , wherein, in the step of forming the first solution comprising the internal crosslinking agent, and the acrylic acid monomers having acid groups of which at least a part are neutralized, the content of the internal crosslinking agent is 0.01 parts by weight to 5 parts by weight, based on 100 parts by weight of the acrylic acid monomers. 
     
     
       13. The method for preparing superabsorbent polymer according to  claim 11 , wherein, in the step of crosslinking polymerization of a monomer composition comprising the first solution and the second solution, the content of the second solution is 1 part by weight to 100 parts by weight, based on 100 parts by weight of the first solution included in the monomer composition. 
     
     
       14. The superabsorbent polymer according to  claim 7 , wherein the internal crosslinking agent comprises one or more selected from the group consisting of polyethyleneglycol diacrylate(PEGDA), glycerin diacrylate glycerin triacrylate, non-modified or ethoxylated trimethylol propane triacrylate(TMPTA), hexanedioldiacrylate, and triethyleneglycol diacrylate.